The most common means for anesthetizing maxillary teeth is the use of an infiltration injection. For example, the patient may receive a needle penetration and injection of a local anesthetic solution at the approximate apex of the root on the buccal surface of a tooth (or teeth) to be treated. A maxillary palatal injection of dental local anesthetic can be used for regional block anesthesia of teeth. The patient may also receive a maxillary palatal injection of local anesthesia in order to effect regional nerve blocks.
Dental anxiety, including needle or shot discomfort and phobia, is a long-standing barrier to regular dental care. In a survey conducted by the American Dental Association, 27% of the people surveyed indicated “fear of pain” as a reason to avoid dental visits. Needle injection of local anesthetic is recognized as the most anxiety-provoking procedure in dentistry for children and adults. Not only can the injection of local anesthetics produce fear, pain and an increase in blood pressure, but the increased stress of injection can result in fainting, hyperventilation, convulsions, shock, hypertension, cardiac arrest, respiratory collapse, acute allergic reaction to preservatives, bronchospasm, angina, and organ system toxicity in medically compromised patients. Further, local injections into target nerves can sometimes lead to permanent numbness as a result of needles damaging and/or cutting nerves. In rare cases, a severe overdose of injectable anesthetic or accidental, rapid intravascular injection of the anesthetic can even lead to death. The act of injecting is invasive (conceptually, psychologically, and physically) and is a major reason worldwide why people avoid regular dental care and see their dentists only in an emergency. In fact, some studies indicate that millions of people in the US are afraid of dental treatments because of pain. Without regular dental care, tooth caries, gum disease and oral cancer may be left undetected and can result in infection and serious, systemic health issues.
In addition, the risk of exposure to bloodborne pathogens via needlesticks is a recognized occupational hazard in dentistry. Since 1991, the Occupational Safety and Health Administration (“OSHA”) has enforced a Bloodborne Pathogens Standard that requires employers to identify, evaluate and implement safer medical devices to eliminate or minimize employee exposure to bloodborne pathogens. The standard was revised in 2001 when Congress passed the Needlestick Safety and Prevention Act. The Act set forth in greater detail employers' obligations under the Bloodborne Pathogens standard and specifically indicated that a “safer medical device” includes needleless systems. Thus, further incentive exists to develop anesthetics that can be delivered without the use of needles and comply with U.S. federally mandated engineered work practice controls.
Lidocaine, the most widely used local dental anesthetic today, was first introduced in the 1940s. Despite many attempts at developing needle-free anesthetic, the only widely-used non-injectable, subsurface local anesthetic commercially available today is Oraqix® gel. While Oraqix® can be used in periodontal pockets during scaling or root-planing procedures, it does not provide adequate anesthesia for use in procedures such as filling, crowns and root canals. Further, while many advances in the comfort of dentistry have been made, such as behavior modification therapy, topical numbing around the injection site, nitrous oxide, hypnosis, and TENS units, none of these advances has eliminated the need for needle injection.
Nasal administration of anesthetics has also been disclosed, for example, in U.S. Pat. No. 6,413,499.
Thus, there remains a need for alternative and effective anesthetics. In particular, there remains a need for alternative and effective anesthetics and means for administering such anesthetics to a patient in order to anesthetize the patient's teeth without creating extra oral soft tissue numbness, discomfort, or phobia in the patient.